Cooling systems and heat exchangers for cooling computer components

ABSTRACT

Computer systems having heat exchangers for cooling computer components are disclosed herein. The computer systems include a computer cabinet having an air inlet, an air outlet spaced apart from the air inlet, and a plurality of computer module compartments positioned between the air inlet and the air outlet. The air inlet, the air outlet, and the computer module compartments define an air flow path through the computer cabinet. The computer systems also include a heat exchanger positioned between two adjacent computer module compartments. The heat exchanger includes a plurality of heat exchange elements canted relative to the air flow path.

CROSS-REFERENCE TO APPLICATION(S) INCORPORATED BY REFERENCE

The present application is a divisional of U.S. patent application Ser.No. 12/862,002 filed Aug. 24, 2010, and entitled “COOLING SYSTEMS ANDHEAT EXCHANGERS FOR COOLING COMPUTER COMPONENTS,” which is a divisionalof U.S. patent application Ser. No. 11/958,114 filed Dec. 17, 2007, andentitled “COOLING SYSTEMS AND HEAT EXCHANGERS FOR COOLING COMPUTERCOMPONENTS,” each of which is incorporated herein in its entirety byreference.

TECHNICAL FIELD

The present disclosure relates generally to cooling systems and heatexchangers for cooling electronic components in computer systems.

BACKGROUND

Supercomputers and other large computer systems typically include alarge number of computer modules housed in cabinets arranged in banks.The computer modules are typically positioned in close proximity to eachother. During operation, the close proximity can make dissipating heatgenerated by the modules difficult. If not dissipated, the heat candamage the modules or significantly reduce system performance.

One conventional technique for computer module cooling includes drawingair into the cabinet to cool the computer modules and discharging theheated air to the room. One shortcoming of this technique, however, isthat the heat capacity of the cooling air can quickly become saturated.As a result, some of the computer modules may not be adequately cooled.Accordingly, there is a need to effectively dissipate heat generated bycomputer modules during operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a partially schematic elevation view of a computer systemhaving internal heat exchangers configured in accordance with anembodiment of the invention.

FIG. 1B is an enlarged perspective view of a heat exchanger havingcanted heat exchange elements configured in accordance with anembodiment of the invention.

FIG. 1C is an enlarged, cross-sectional side view of two heat exchangeelements from the heat exchanger of FIG. 1B, configured in accordancewith an embodiment of the invention.

FIG. 2 is a cross-sectional side view of a heat exchange element havingnon-identical internal channels configured in accordance with anotherembodiment of the invention.

FIG. 3 is a front view of a heat exchange element having a plurality offin configurations positioned along an air flow path in accordance withanother embodiment of the invention.

FIG. 4 is a perspective view of a heat exchanger having partitionedinlet and/or outlet manifolds configured in accordance with anotherembodiment of the invention and suitable for use in the computer systemof FIG. 1A.

FIG. 5 is a top view of a heat exchanger having counter-flowing workingfluids configured in accordance with a further embodiment of theinvention and suitable for use in the computer system of FIG. 1A.

DETAILED DESCRIPTION

The following disclosure describes several embodiments of coolingsystems for use with supercomputers and/or other computer systems.Persons of ordinary skill in the art will understand, however, that theinvention can have other embodiments with additional features, orwithout several of the features shown and described below with referenceto FIGS. 1-5. In the Figures, identical reference numbers identifystructurally and/or functionally identical, or at least generallysimilar, elements.

FIG. 1A is a partially schematic elevation view of a computer system 100having a plurality of internal heat exchangers 118 (identifiedindividually as heat exchangers 118 a-d) configured in accordance withan embodiment of the invention. The computer system 100 can include acomputer cabinet 102 in a room 101. Working fluid lines 106 (identifiedindividually as a supply line 106 a and a return line 106 b) connect thecomputer cabinet 102 to a heat removal system 104. In the illustratedembodiment, the heat removal system 104 is situated in the room 101 andspaced apart from the computer cabinet 102. In other embodiments,however, the heat removal system 104 can be integrated into the computercabinet 102, positioned outside the room 101, or situated in othersuitable places.

The computer cabinet 102 can include an air inlet 114 for receivingcooling air from the room 101 or a floor plenum (not shown), an airoutlet 116 for discharging air to the room 101, and a plurality ofcomputer module compartments 120 (identified individually as first,second, and third computer module compartments 120 a-c, respectively)arranged vertically between the air inlet 114 and the air outlet 116 ina chassis 110. Individual computer module compartments 120 hold aplurality of computer modules 112 oriented edgewise with respect to theflow of cooling air through the chassis 110.

The computer cabinet 102 can also hold a plurality of heat exchangers118 in the chassis 110. As described in greater detail below withreference to FIGS. 1B-4, the individual heat exchangers 118 can beconfigured to receive a working fluid (not shown) from the heat removalsystem 104 via the supply line 106 a. After flowing through the heatexchangers 118, the working fluid returns to the heat removal system 104via the return line 106 b. The working fluid can includehydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons,ammonia, and/or other suitable refrigerants known in the art. Theworking fluid can include a vapor phase fluid, a liquid phase fluid, ora two-phase fluid when flowing through the heat exchangers 118.

The computer cabinet 102 can additionally include an air mover 130(e.g., a fan) positioned proximate to the air inlet 114 to facilitatemovement of the cooling air through the chassis 110 along a flow path117. The air mover 130 can draw air from the room 101 or a floor plenuminto the chassis 110 through the air inlet 114. The air then flowsthrough the chassis 110 past the computer modules 112, and exits thechassis 110 via the air outlet 116.

The heat removal system 104 can include a pump 124 in fluidcommunication with a condenser 122. The condenser 122 can be ashell-and-tube type heat exchanger, a plate-and-frame type heatexchanger, or other suitable type of heat exchanger known in the art.The condenser 122 can include a working fluid inlet 126 a for receivingheated working fluid returning from the computer cabinet 102, and aworking fluid outlet 126 b for supplying cooled working fluid to thepump 124. The condenser 122 can also include a coolant inlet 128 a and acoolant outlet 128 b for circulating chilled water, cooling water, orother suitable coolant (not shown) to cool the working fluid. The pump124 can include a positive displacement pump, a centrifugal pump, orother suitable type of pump for circulating the working fluid back tothe heat exchangers 118 via the supply line 106 a.

During operation of the computer system 100, the air mover 130 draws airinto the chassis 110 through the air inlet 114. The first heat exchanger118 a cools the air before it flows into the first compartment 120 a. Asthe air flows through the first compartment 120 a, the computer modules112 in the first compartment 120 a transfer heat to the air. The secondheat exchanger 118 b then cools the air before the air passes into thesecond compartment 120 b by absorbing heat from the air into the workingfluid. The air is similarly cooled by the third heat exchanger 118 cbefore flowing into the third compartment 120 c. The fourth heatexchanger 118 d then cools the heated air leaving the third compartment120 c before the air is discharged to the room 101 via the air outlet116.

In one embodiment, the working fluid is in phase transition betweenliquid and vapor as the working fluid leaves the heat exchangers 118. Inother embodiments, the working fluid can have other phase conditions atthis time. The heated working fluid from the heat exchangers 118 returnsto the condenser 122 via the return line 106 b. The coolant in thecondenser 122 cools the working fluid before the pump 124 circulates theworking fluid back to the heat exchangers 118.

Only a single computer cabinet 102 is shown in FIG. 1A for purposes ofillustration and ease of reference. In other embodiments, however,supercomputers and other large computer systems can include a pluralityof computer cabinets arranged in banks or other configurations. In suchembodiments, the heat removal system 104 can provide working fluid toone or more of the computer cabinets 102 via an appropriately configuredpiping circuit. Further, although the heat exchangers 118 have beendescribed above in the context of working fluid-type heat exchangers, inother embodiments, other types of heat exchangers can be used tointer-cool the air moving through the compartments 120 without departingfrom the spirit or scope of the present invention.

FIG. 1B is an enlarged perspective view of one of the heat exchangers118 configured in accordance with an embodiment of the invention. Theheat exchanger 118 can include a plurality of heat exchange elements 132extending between and in fluid communication with an inlet manifold 134and an outlet manifold 135. Although four heat exchange elements 132 areshown in FIG. 1B, in other embodiments, the heat exchanger 118 caninclude more or fewer heat exchange elements 132 depending on a numberof factors including heat load, cost, manufacturability, etc.

The inlet manifold 134 can include a distribution section 137 cextending between an inlet port 137 a and a capped inlet end 137 b. Inthe illustrated embodiment, the distribution section 137 c includes agenerally tubular structure (e.g., a section of a pipe or a tube) with aplurality of first slots 137 d arranged along a length of thedistribution section 137 c. The first slots 137 d are configured toreceive first end portions of the heat exchange elements 132. In otherembodiments, the distribution section 137 c can have otherconfigurations to accommodate other factors.

In the illustrated embodiment, the outlet manifold 135 is generallysimilar to the inlet manifold 134. For example, the outlet manifold 135includes a collection section 139 c extending between an outlet port 139a and a capped outlet end 139 b. The collection section 139 c includes agenerally tubular structure with a plurality of second slots 139 darranged along a length of the collection section 139 c in one-to-onecorrespondence with the first slots 137 d. In other embodiments, theoutlet manifold 135 can have other configurations, including others thatdiffer from the inlet manifold 134. For example, the collection section139 c can have a different cross-sectional shape and/or a different sizethan the distribution section 137 c.

The individual heat exchange elements 132 can include a plurality offins 142 extending from a passage portion 140. A first end portion 132 aof the passage portion 140 is coupled to the inlet manifold 134 via thefirst slots 137 d, and a second end portion 132 b of the passage portion140 is coupled to the outlet manifold 135 via the second slots 139 d. Inthe illustrated embodiment, the passage portion 140 extends into boththe inlet manifold 134 and the outlet manifold 135. In otherembodiments, however, the ends of the passage portion 140 can begenerally flush with the first and/or second slots 137 d, 139 d. Furtherdetails of several embodiments of the passage portion 140 are describedbelow with reference to FIG. 1C.

FIG. 1C is an enlarged side view of two of the heat exchange elements132 of FIG. 1B, configured in accordance with one embodiment of theinvention. As illustrated in FIG. 1C, the heat exchange elements 132 canbe at least generally parallel to each other with a gap D (e.g., fromabout 1 cm to about 2 cm, or any other desired spacing) therebetween. Inother embodiments, however, at least some of the heat exchange elements132 can be nonparallel to the other heat exchange elements 132. The gapD can form an air passage 136 in fluid communication with the air flowpath 117. The air passage 136 allows cooling air to flow past the heatexchange elements 132 during operation of the computer system 100.

In certain embodiments, individual heat exchange elements 132 can becanted relative to the incoming air flow path 117 a. For example, asillustrated in FIG. 1C, the heat exchange elements 132 can form an angleA of from about 10° to about 45°, preferably from about 15° to about40°, and more preferably about 20° to about 30° relative to the air flowpath 117 a. In other embodiments, the heat exchange elements 132 and theair flow path 117 a can form other suitable angles. Each of the heatexchange elements 132 can form the same angle or different anglesrelative to the air flow path 117. For example, the angles can increaseor decrease (e.g., linearly, exponentially, etc.) from one heat exchangeelement 132 to another.

The individual heat exchange elements 132 can include a plurality ofinternal fluid channels 144 (identified individually as first, second,third, and fourth internal channels 144 a-d, respectively). In theillustrated embodiment, the internal channels 144 have generally thesame cross-sectional shape, e.g., a generally rectangular shape, andgenerally the same cross-sectional area. In other embodiments, however,the internal channels 144 can have other cross-sectional shapes, such astriangular shapes, circular shapes, oval shapes, and/or other suitableshapes and/or cross-sectional areas. In further embodiments, theinternal channels 144 can have non-identical configurations, asdescribed in more detail below with reference to FIG. 2.

Referring to FIG. 1B and FIG. 1C together, in operation, a working fluid(not shown) flows into the inlet manifold 134 via the inlet port 137 a,as indicated by the arrow 131 a. The inlet manifold 134 distributes theworking fluid to the internal channels 144 at the first end 132 a ofeach of the heat exchange elements 132. The working fluid flows acrossthe heat exchange elements 132 from the first end 132 a toward thesecond end 132 b. As the working fluid flows across the heat exchangeelements 132, the working fluid absorbs heat from cooling air flowingthrough the air passage 136 and/or past the fins 142. As a result, inone embodiment, the working fluid can be at least partially vaporized(i.e., a two-phase fluid) at the outlet manifold 135. In otherembodiments, the working fluid can be sub-cooled at the outlet manifold135. In further embodiments, the working fluid can be substantiallycompletely vaporized at the outlet manifold 135. In all theseembodiments, the collection section 139 c of the outlet manifold 135collects the heated working fluid and returns the heated working fluidto the heat removal system 104 (FIG. 1A) via the outlet port 139 a, asindicated by the arrow 131 b.

Canting the heat exchange elements 132 can improve heat distributionalong a length L (FIG. 1C) of the heat exchange elements 132. Forexample, as the cooling air flows past the heat exchange elements 132,the working fluid in one of the internal channels 144 (e.g., the fourthinternal channel 144 d) can absorb heat from air streams that have notbeen significantly cooled by working fluid flowing through otherinternal channels 144 (e.g., the first, second, and/or third internalchannels 144 a-c). As a result, heat distribution along the length L ofthe heat exchange element 132 can be more efficient than with heatexchange elements arranged parallel to the air flow. The canted heatexchange elements 132 can also increase the heat transfer area withoutsignificantly affecting the height of the heat exchanger 118.Furthermore, the canted heat exchange elements 132 can improve energydistribution in the computer cabinet 102 (FIG. 1A) because the cantedheat exchange elements 132 can deflect cooling air to other parts of thecomputer cabinet 102 during operation, as indicated by the arrow 117.

FIG. 2 is a cross-sectional side view of a heat exchange element 232having non-identical internal channels configured in accordance withanother embodiment of the invention. As illustrated in FIG. 2, the heatexchange element 232 can include a plurality of internal channels 244(identified individually as first, second, third, and fourth internalchannel 244 a-d, respectively), and at least one internal channel 244has a different internal configuration than others. For example, thecross-sectional area of the internal channels 244 can sequentiallydecrease from the first internal channel 244 a to the fourth internalchannel 244 d. In other embodiments, the first and second internalchannels 244 a-b can have a first cross-sectional area, and the thirdand fourth internal channels 244 c-d can have a second cross-sectionalarea, smaller than the first cross-sectional area. As the foregoingillustrates, in further embodiments, the internal channels 244 can havedifferent cross-sectional shapes and/or other arrangements.

In operation, the different internal configurations of the internalchannels 244 can allow the working fluid to have different mass flowrates when flowing through the internal channels 244. For example, inthe illustrated embodiment, the first internal channel 244 a has alarger cross-sectional area than that of the second internal channel 244b. As a result, the mass flow rate of working fluid through the firstinternal channel 244 a will be greater than the mass flow rate of theworking fluid through the second internal channel 244 b for a givenfluid pressure.

Controlling the flow rate of the working fluid flowing throughindividual internal channels 244 can improve heat transfer performanceof the heat exchange element 232. The inventor has recognized that, incertain situations, the working fluid flowing through the first internalchannel 244 a can be completely vaporized before and/or when it reachesthe outlet manifold 135 (FIG. 1B). The completely vaporized workingfluid typically cannot efficiently transfer heat because of a low heatcapacity. By increasing the flow rate of the working fluid flowingthrough the first internal channel 244 a, the working fluid can be atleast a two-phase fluid when it reaches the outlet manifold 135, thusimproving the heat transfer efficiency.

In other embodiments, the heat exchange element 232 can include otherfeatures that affect the mass flow rate of the working fluid in theinternal channels 244. For example, individual internal channels 244 caninclude an orifice, a nozzle, and/or other flow restricting components.In another example, the heat exchange element 232 can include a barrier(not shown) that partially blocks the cross-section of at least one ofthe internal channels 244.

FIG. 3 is a front view of a heat exchange element 332 having a finconfiguration configured in accordance with a further embodiment of theinvention. In this embodiment, the heat exchange element 332 includes afirst fin portion 342 a and a second fin portion 342 b arranged alongthe air flow path 117. The first fin portion 342 a can include aplurality of first fins 343 a, and the second fin portion 342 b caninclude a plurality of second fins 343 b, different than the first fins343 a. For example, in the illustrated embodiment, the second finportion 342 b can have a larger number of fins 343 b than the first finportion 342 a. In another embodiment, the second fin portion 342 b caninclude different types of fins than the first fin portion 342 a (e.g.,the second fins 343 b can have different heights, thicknesses, etc). Ina further embodiment, the second fins 343 b can have a higher heatconductance than the first fins 343 a. In any of these embodiments, thesecond fin portion 342 b can have a higher heat transfer coefficientthat the first fin portion 342 a.

Having different fin configurations along the air flow path 117 canimprove the heat transfer efficiency between the working fluid and thecooling air. The inventor has recognized that if the fins have the sameconfiguration along the length L of the heat exchange element 332, theworking fluid flowing through the fourth internal channel 144 d (FIG.1C) is likely to be mostly liquid when it reaches the outlet manifold135 (FIG. 1B). Thus, the heat transfer between the working fluid and thecooling air is limited because the mostly liquid working fluid typicallyhas a latent heat capacity much lower than its heat of vaporization. Theinventor has further recognized that the limiting factor in the heattransfer between the working fluid and the cooling air is the heattransfer rate between the fins and the cooling air. Thus, by increasingthe heat transfer efficiency and/or capability of the second fin portion342 b, the heat transfer between the working fluid in the fourthinternal channel 144 d and the cooling air can be improved.

FIG. 4 is a partially exploded perspective view of a heat exchanger 418configured in accordance with another embodiment of the invention andsuitable for use in the computer system 100 of FIG. 1A. Many features ofthe heat exchanger 418 can be at least generally similar in structureand function to the heat exchangers 118 describe above. For example, theheat exchanger 418 can include a plurality of heat exchange elements 432extending between an inlet manifold 434 and an outlet manifold 435. Theindividual heat exchange elements 432 can include a plurality of fins442 extending from a passage portion 440. The passage portion 440 can begenerally similar to the passage portion 140 of FIGS. 1B and 1C, or thepassage portion 240 of FIG. 2.

The inlet manifold 434 can include a distribution section 437 cextending between an inlet opening 437 a and a capped inlet end 437 b.The inlet manifold 434 can also include an inlet divider 448 extendingbetween the inlet opening 437 a and the inlet end 437 b. The inletdivider 448 separates the distribution section 437 c into a first inletvolume 450 a and a second inlet volume 450 b. The inlet divider 448 alsoseparates the inlet opening 437 a into a first inlet port 452 a and asecond inlet port 452 b.

In the illustrated embodiment, the outlet manifold 435 is generallysimilar to the inlet manifold 434. For example, the outlet manifold 435includes a collection section 439 c extending between an outlet opening439 a and a capped outlet end 439 b. The outlet manifold 435 can alsoinclude an outlet divider 458 that separates the collection section 439c into a first outlet volume 460 a and a second outlet volume 460 b. Theoutlet divider 458 also separates the outlet opening 439 a into a firstoutlet port 462 a and a second outlet port 462 b.

The inlet and outlet dividers 448, 458 cooperate to separate theinternal channels 144 (FIGS. 1C) of individual heat exchange elements432 into a first channel portion 444 a corresponding to the firstinlet/outlet volumes 450 a, 460 a and a second channel portion 444 bcorresponding to the second inlet/outlet volumes 450 b, 460 b. Thus, thefirst inlet volume 450 a, the first channel portion 444 a, and the firstoutlet volume 460 a form a first flow path of the heat exchanger 418.Similarly, the second inlet volume 450 b, the second channel portion 444b, and the second outlet volume 460 b form a second flow path of theheat exchanger 418. The first and second flow paths are isolated fromeach other and arranged along the air flow path 117.

In operation, the heat exchanger 418 can receive a first working fluidportion via the first inlet port 452 a, as indicated by arrow 470 a, anda second working fluid portion via the second inlet port 452 b, asindicated by arrow 472 a. The first and second inlet volumes 450 a-bdistribute the first and second working fluid portions to the first andsecond channel portions 444 a-b, respectively. The first and secondworking fluid portions flow across the heat exchange elements 432, asindicated by arrows 470 b and 472 b, respectively. As the first andsecond working fluid portions flow across the heat exchange elements432, they absorb heat from the cooling air flowing past the fins 442.The first and second outlet volumes 460 a-b collect the heated first andsecond working fluid portions and returns them to the heat removalsystem 104 (FIG. 1A) via the first and second outlet ports 462 a and 462b, respectively, as indicated by arrows 470 c and 472 c, respectively.

The first and second working fluid portions can have different physicalcharacteristics. For example, in one embodiment, the first working fluidportion can have a mass flow rate that is less than the second workingfluid portion. In another embodiment, the first working fluid portioncan have a higher heat transfer coefficient than the second workingfluid portion. In a further embodiment, the first working fluid portioncan have a lower boiling point than the second working fluid portion. Inyet another embodiment, the first working fluid portion can have ahigher heat of vaporization than the second working fluid portion.

By controlling the physical characteristics of the first and secondworking fluid portions, the heat exchanger 418 can have improved heattransfer performance compared to conventional heat exchangers. Theinventor has recognized that if the same working fluid is flowingthrough all the internal channels of the heat exchange elements 432, theworking fluid in those channels proximate to the incoming cooling air islikely to be completely vaporized, while the working fluid in otherchannels spaced apart from the incoming cooling air may still be inliquid phase. Thus, by selecting appropriate heat transfercharacteristics of the first and second working fluids, an operator canimprove the heat transfer between the working fluid and the cooling air.

Although the inlet divider 448 and the outlet divider 458 areillustrated in FIG. 4 as being generally perpendicular to the air flowpath 117, in other embodiments, at least one of the inlet divider 448and the outlet divider 458 can be canted relative to the air flow path117. In further embodiments, at least one of the inlet divider 448 andthe outlet divider 458 can be omitted, and/or at least one of the firstand second inlet/outlet volumes 450 a-b, 460 a-b can be standalonestructures. For example, the first and second inlet volumes 450 a-b caneach include a generally tubular structure and spaced apart from eachother.

FIG. 5 is a top view of a heat exchanger 518 configured in accordancewith a further embodiment of the invention and suitable for use in thecomputer system 100 of FIG. 1A. Many features of the heat exchanger 518can be at least generally similar in structure and function to the heatexchangers 118 describe above. For example, the heat exchanger 518 caninclude a plurality of heat exchange elements 532 (identifiedindividually as first, second, third, and fourth heat exchange elements532 a-d, respectively) extending between a first manifold 534 and asecond manifold 535. The individual heat exchange elements 532 caninclude a passage portion 540 and have a plurality of fins 542 extendingfrom the passage portion 540. The passage portion 540 can be generallysimilar to the passage portion 140 of FIGS. 1B and 1C, or FIG. 2.

The first manifold 534 can include a first intermediate section 537 cextending between a first opening 537 a and a capped first end 537 b.The first manifold 534 can also include a first divider 548 extendingbetween the first opening 537 a and the first end 537 b. The firstdivider 548 separates the first intermediate section 537 c into a firstdistribution volume 550 a and a first collection volume 550 b. The firstdivider 548 also separates the first opening 537 a into a first inletport 552 a and a first outlet port 552 b.

The first distribution volume 550 a and the first collection volume 550b are in fluid communication with only a portion of the heat exchangeelements 532. For example, in the illustrated embodiment, the firstdistribution volume 550 a is in fluid communication with the second andfourth heat exchange elements 532 b, 532 d, and the first collectionvolume 550 b is in fluid communication with the first and third heatexchange elements 532 a, 532 c. In other embodiments, the first manifold534 can also have other flow configurations.

The second manifold 535 can include a second intermediate section 539 cextending between a second opening 539 a and a capped second end 539 b.The second manifold 535 can also include a second divider 558 extendingbetween the second opening 539 a and the second end 539 b. The seconddivider 558 separates the second intermediate section 539 c into asecond distribution volume 560 a and a second collection volume 560 b.The second divider 558 also separates the second opening 539 a into asecond inlet port 562 a and a second outlet port 562 b.

The second distribution volume 560 a and the second collection volume560 b are in fluid communication with only a portion of the heatexchange elements 532. For example, in the illustrated embodiment, thesecond distribution volume 560 a is in fluid communication with thefirst and third heat exchange elements 532 a, 532 c, and the secondcollection volume 560 b is in fluid communication with the second andfourth heat exchange elements 532 b, 532 d. In other embodiments, thesecond manifold 535 can also have other flow configurations.

The heat exchanger 518 can thus have a first flow path from the firstinlet port 552 a to the second outlet port 562 b via the firstdistribution volume 550 a, the second and fourth heat exchange elements532 b, 532 d, and the second collection volume 560 b. The heat exchanger518 can also have a second flow path from the second inlet port 562 a tothe first outlet port 552 b via the second distribution volume 560 a,the first and third heat exchange elements 532 a, 532 c, and the firstcollection volume 550 b.

In operation, the heat exchanger 518 can receive a first working fluidportion via the first inlet port 552 a, as indicated by arrow 570 a, anda second working fluid portion via the second inlet port 562 a, asindicated by arrow 572 a. The first and second distribution volumes 550a, 560 a distribute the first and second working fluid portions tocorresponding heat exchange elements 532. The first working fluidportion then flows across the second and fourth heat exchange elements532 b, 532 d in a first direction, as indicated by arrow 570 b. Thesecond working fluid portion then flows across the first and third heatexchange elements 532 a, 532 c in a second direction, as indicated byarrow 572 b. In the illustrated embodiment, the second direction isgenerally opposite the first direction. In other embodiments, the firstand second directions can form an angle of about 120° to about 180°. Asthe first and second working fluid portions flow across the heatexchange elements 532, the cooling air flowing past the fins 542 heatsthe first and second working fluid portions. The first and secondcollection volumes 550 b, 560 b collect the heated first and secondworking fluid portions and return them to the heat removal system 104(FIG. 1A) via the first and second outlet ports 552 b, 562 b, asindicated by arrows 570 c, 572 c, respectively.

By flowing the first and second working fluid portions in generallyopposite directions, the heat exchanger 518 can have improved heattransfer efficiency compared to conventional heat exchangers. Theinventor has recognized that the heat transfer efficiency decreases asthe first and/or second portions of working fluid flow across the heatexchange elements. Thus, if the first and second working fluid portionsflow in the same direction, one side of the heat exchanger 518 may haveinsufficient heat transfer. However, by alternating the flow directionsof the first and second working fluid portions, the heat transferefficiency between the first and second working fluid portions and thecooling air can be improved.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. For example, the heat exchangersshown in FIGS. 4 and 5 can also incorporate the heat exchange elementsshown in FIGS. 2 and 3. In another example, the heat exchanger shown inFIG. 1B can also incorporate the inlet/outlet manifolds of FIG. 4 orFIG. 5. Further, while advantages associated with certain embodiments ofthe invention have been described in the context of those embodiments,other embodiments may also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages to fall within thescope of the invention. Accordingly, the invention is not limited,except as by the appended claims.

I claim:
 1. A computer system, comprising: a computer cabinet having aplurality of computer module compartments positioned between an airinlet and an air outlet, wherein the air inlet, the air outlet, and thecomputer module compartments define an air flow path through thecomputer cabinet; and a heat exchanger positioned between two adjacentcomputer module compartments, the heat exchanger including: a firstmanifold having a first divider separating the first manifold into afirst inlet volume and a first outlet volume; a second manifold having asecond divider separating the second manifold into a second inlet volumeand a second outlet volume; a first heat exchange element in fluidcommunication with the first inlet volume and the second outlet volumewhile being isolated from the second inlet volume and the first outletvolume; and a second heat exchange element in fluid communication withthe second inlet volume and the first outlet volume while being isolatedfrom the first inlet volume and the second outlet volume, wherein thefirst inlet volume, the first heat exchange element, and the secondoutlet volume at least partially define a first flow path and the secondinlet volume, the second heat exchange element, and the first outletvolume at least partially define a second flow path in fluid isolationfrom the first flow path.
 2. The computer system of claim 1, furthercomprising a first working fluid portion in the first flow path and asecond working fluid portion in the second flow path, and wherein thefirst working fluid portion and the second working fluid portion havedifferent flow directions when flowing through the first and second heatexchange elements.
 3. The computer system of claim 1, further comprisinga first working fluid portion in the first flow path and a secondworking fluid portion in the second flow path, and wherein computersystem further includes a directing means for directing the firstworking fluid portion to flow through the first heat exchange element ina first direction and the second working fluid portion to flow throughthe second heat exchange element in a second direction opposite of thefirst direction.
 4. The computer system of claim 1 wherein the firstflow path is in fluid isolation from the second flow path.
 5. Thecomputer system of claim 1, further comprising a first working fluidportion in the first flow path and a second working fluid portion in thesecond flow path, wherein the first working fluid portion has a firstphysical characteristic and the second working fluid portion has asecond physical characteristic that is different than the first physicalcharacteristic.
 6. A method for operating a computer cabinet having aplurality of computer module compartments positioned between an airinlet and an air outlet and a heat exchanger positioned between twoadjacent computer module compartments, the method comprising: flowing afirst working fluid portion along a first inlet volume in a firstmanifold of the heat exchanger; flowing a second working fluid portionalong a second inlet volume in a second manifold of the heat exchanger,wherein the second manifold is spaced apart from the first manifold;flowing the first working fluid portion from the first inlet volumealong a first flow path in a first internal channel of an individualheat exchange element of the heat exchanger; flowing the second workingfluid portion from the second inlet volume along a second flow path in asecond internal channel of the individual heat exchange element of theheat exchanger, the first and second internal channels being in fluidisolation from each other; flowing the first working fluid portion fromthe first internal channel into a first outlet volume of the secondmanifold; flowing the second working fluid portion from the secondinternal channel into a second outlet volume of the first manifold,wherein the first manifold includes a first divider separating the firstmanifold into the first inlet volume and the second outlet volume,wherein the second manifold includes a second divider separating thesecond manifold into the first outlet volume and the second inletvolume, wherein the first inlet volume is positioned toward a first endof the individual heat exchange element and the second inlet volume ispositioned toward a second end of the individual heat exchange elementopposite the first end, wherein the first outlet volume is positionedtoward the second end of the individual heat exchange element and thesecond outlet volume is positioned toward the first end of theindividual heat exchange element, and wherein the first and secondworking fluids portions flow in generally opposite directions across theindividual heat exchange element.
 7. The method of claim 6, furthercomprising controlling at least one characteristic of at least one ofthe first and second working fluid portions.
 8. The method of claim 6,further comprising controlling a flow rate, a heat transfer coefficient,a boiling point, and/or a heat of vaporization of at least one of thefirst and second working fluid portions.
 9. The method of claim 6,further comprising drawing air into the computer cabinet via the airinlet, flowing the air through the heat exchanger and past theindividual heat exchange element, and discharging the air from thecomputer cabinet via the air outlet.
 10. The method of claim 6, furthercomprising flowing air along an air flow path through the heat exchangerand past the individual heat exchange element, wherein the first andsecond flow paths are arranged sequentially along the air flow path. 11.A computer system, comprising: a computer cabinet having a plurality ofcomputer module compartments positioned between an air inlet and an airoutlet, wherein the air inlet, the air outlet, and the computer modulecompartments define an air flow path through the computer cabinet; and aheat exchanger positioned between two adjacent computer modulecompartments, the heat exchanger including: a first manifold having afirst divider separating the first manifold into a first inlet volumeand a first outlet volume; a second manifold having a second dividerseparating the second manifold into a second inlet volume and a secondoutlet volume; and at least one heat exchange element positioned betweenthe first manifold and the second manifold, wherein the individual heatexchange element includes a first internal channel portion and a secondinternal channel portion, wherein the first internal channel portion isin fluid communication with the first inlet volume and the second outletvolume, and wherein the second internal channel portion is in fluidcommunication with the second inlet volume and the first outlet volume.12. The computer system of claim 11 wherein the first inlet volume, thefirst internal channel portion, and the second outlet volume at leastpartially define a first flow path, wherein the second inlet volume, thesecond internal channel portion, and the first outlet volume at leastpartially define a second flow path, and wherein the first flow path isin fluid isolation from the second flow path.
 13. The computer system ofclaim 12 wherein the first and second flow paths are arrangedsequentially along the air flow path.
 14. The computer system of claim12, further comprising a first working fluid portion in the first flowpath and a second working fluid portion in the second flow path, whereinthe first working fluid portion and the second working fluid portionhave different flow directions when flowing through the individual heatexchange element.
 15. The computer system of claim 12, furthercomprising a first working fluid portion in the first flow path and asecond working fluid portion in the second flow path, wherein the firstworking fluid portion has a first physical characteristic and the secondworking fluid portion has a second physical characteristic that isdifferent than the first physical characteristic.
 16. The computersystem of claim 12, further comprising a first working fluid portion inthe first flow path and a second working fluid portion in the secondflow path, wherein the first working fluid portion has at least one of adifferent flow rate, a different heat transfer coefficient, a differentboiling point, or a different heat of vaporization than the secondworking fluid portion.
 17. The computer system of claim 11 wherein theindividual heat exchange element carries a plurality of fins on anexternal portion thereof.
 18. The computer system of claim 11, whereinthe at least one heat exchange element includes a plurality of heatexchange elements positioned between the first manifold and the secondmanifold, and wherein all of the heat exchange elements are functionallyidentical.